Treatment of hydrocarbons



Patented Dec. 1, 1936 UNITED STATE TREATMENT OF HYDROCARBONS Seymour W. Ferris, Aldan, Pa., assignor to The Atlantic Refining Company, Philadelphia, Pa.,

a corporation of Pennsylvania No Drawing. Application March 30, 1933, Serial No. 663,552

9 Claims.

This invention relates to the art of hydrocarbon oil refining and has particular reference to the separation of hydrocarbon oils, especially crude petroleum or petroleum products, into fractions 5 of different chemical composition while of approximately the same distillation range.

In accordance with my invention, hydrocarbon oils, particularly oils of substantial viscosity, are separated into various fractions by means of sel lective solvents, and more particularly by extrac-' tion with a solvent from the group comprising the monoand poly-halogen substituted aliphatic oxyand oxo-compounds, preferably the monocompounds. My invention also contemplates mixtures of solvents containing substantial amounts of the compounds aforesaid. I mean by this classification to include particularly aliphatic organic compounds containing only carbon, hydrogen, oxygen and halogen in which the oxygen .and halogen are each linked directly to carbon, such as the halogen derivatives of the aliphatic alcohols, ethers, aldehydes, ketones, acids and esters. Examples of this class of compounds are ethyl chloracetate, chloracetone, and dibrom propyl alcohol.

It is recognized in the art that mineral oils, such as petroleum, comprises essentially a mixture of hydrocarbons of various groups of homologous series of compounds, such for example, as parafiins of the general formula CnH2n+2, olefines of the general formulaCnI-Izn, hydroaromatics and polymethylenes of the same empirical formula, and various other series of compounds of chain and/or ring structures in which the hydrogen to carbon ratio is less than in the foregoing series. A large number of individual compounds of each series and of differing boiling points are present in petroleum.

The various types of crude petroleum, which are generally classified into three groups, namely, parafiinic base, naphthenic or asphaltic base, and mixed base, contain the various series of hydrocarbons mentioned heretofore in different proportions. For example, in the parafiin base crude oils, such as those obtained from the oil fields of Pennsylvania, there is a relatively large proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereas in the naphthenic or asphaltic base crude oils, there ,is a relatively large proportion of hydrocarbons having ring structures and a low hydrogen to carbon ratio. Mixed base crude oils, such as are obtained from the Mid-Continent oil fields, contain hydrocarbons in proportion intermediate these two extremes.

The variance in the proportion of the different series of hydrocarbons in parafiinic, naphthenic, and mixed base oils is evidenced by the physical properties of the various oils and particularly by the relationship of the specific gravity to the visl0 cosity of one oil as compared with another. For example, an oil derived from a Pennsylvania crude and having a viscosity of 400 seconds Saybolt universal at 100 R, will show a-specific gravity at 60 F. of about 0.878, whereas an oil of corresponding viscosity produced from a naphthenic crude, such as one from the Gulf Coast area, will show a specific gravity of about 0.933' at 60 F. The relationship between the viscosity and gravity indicates the degree of parafiinicity or naphthenicity of the oil, and such relationship may be expressed by the viscosity-gravity constant as hereinafter described.

If a given crude petroleum be distilled into successive fractions and the specific gravities and viscosities of the several viscous fractions be determined, it will be found that they conform to the general relationship expressed by the formu1ae log (V- 38) G; 0.24+0.755a'+ 0.022 10g (V' -35.5)

fractionsof the paraflinic crudes than is the constant for fractions of the naphthenic crudes. An article entitled The viscosity-gravity constant of petroleum lubricating oils by J. B. Hill and H. B. Coats, which will be found in vol. 20, page 641 et seq., I. E. C. for June 1928, explains the detera mination of such constant for several typical oils.

The viscosity-gravity constant is, therefore, an index of the paraffinicity of naphthenicity of viscous oils, since when a given crude is distilled, the fractions thereof collected, and the specific gravity and the viscosity of each of the viscous fractions determined, such specific gravities and viscosities substituted in the formula, and the viscosity-gravity constants of the fractions calculated, it will be found that such constants are substantially the same.

The viscosity-gravity constants of the viscous fractions of some of the typical crudes are as follows:

Milltown (Pennsylvania) 0.8067 Burbank (Mid-Continent) 0.83 67 Gaudalupe (Gulf Coast) 0.8635 Mirando (Gulf Coast) 0.9025

While the above figures indicate the viscositygravity constants of specific oils from several types of crudes, it is to be understood that for any particular type of crude such constant may be within a range between values above and below the constant of the typical crude given. For example, viscous oils resulting from the distillation of Mid-Continent crudes have viscosity-gravity constants ranging from about 0.835 to about 0.855, whereas the viscous fractions resulting from distillation of Pennsylvania type crudes range from about 0.805 to 0.828, and in most instances, are below 0.820. Oils are increasingly parafiinic as their viscosity-gravity constants decrease.

My invention is based upon the discovery that oils containing both the parafiinic and the naphthenic series of hydrocarbons may be fractionally extracted with halogen substituted aliphatic oxyand exc -compounds. The various series of hydrocarbons possess a differential solubility in such a solvent, the naphthenic hydrocarbons being more soluble therein than'the paraffinic hydrocarbons. By means of extraction with such solvent, it is therefore possible to effect a partial separation of the naphthenic hydrocarbons from the paraifinic, and to obtain from an oil containing both classes of hydrocarbons, an oil fraction which is more paraffinic than the original oil and one which is more naphthenic. By my invention, for example, it is possible to produce an oil of the quality normally obtained from Appalachian crudes, from crudes of the mixed base type from the Mid-Continent area, and, conversely, to obtain oils from mixed base crudes such as are normally obtained from the naphthenic oils of the Gulf Coast area. any source there may be obtained by my process, oils which are respectively more parafiinic and naphthenic than the oils normally obtained from such source by distillation.

In accordance with my invention, I first mix the oil to be treated with a suitable proportion of the solvent at a temperature such that complete solution is effected and a homogeneous liquid obtained. I then cool the mixture to a temperature at which separation of the liquid into a twolayer system will take place. The upper layer will contain a relatively small amount of solvent dissolved in the parafiinic portion of the oil while the lower layer will contain the more naphthenic oil dissolved in the solvent. Or,- I may agitate the mixture of solvent and oil at temperatures at which the liquids are only partially miscible, and

In general, from oils from aoeasve thereby effect solution of the naphthenic portion of the oil in the solvent. In either of the above procedures I may take advantage of the principles of countercurrent extraction. After extraction, I effect separation of the two layers which form, by any suitable procedure, as for example, by decantation. I then remove from each of the separated layers, the portion of the solvent which each contains by suitable procedure, such as by vacuum distillation, thereby to obtain two oils of similar distillation range but of different chemical composition and different physical properties. Before removing the solvent from the upper and more paraflinic layer, I may add a further quantity of solvent and repeat the extraction, thereby to remove additional naphthenic constituents from said layer.

My invention may be illustrated by the following specific examples:

100 parts of an untreated distillate obtained from a Gulf Coast crude oil and having a viscosity of 612 seconds Saybolt universal at 100 F., a specific gravity at 60 F. of 0.9303, and a viscosity-gravity constant of 0.874 was mixed with 300 parts of chlor-acetone and heated to slightly above the temperature of complete miscibility, i. e., to approximately C. The homogeneous liquid which resulted was cooled, with agitation, to 60 C. and allowed to settle, whereupon a two layer system formed which consisted of an upper undissolved oil layer comprising 60.5 parts. of the mixture and a lower layer of oil dissolved in chlor-acetOn comprising 339.5 parts of the mixture. After separation the layers were each freed of the solvent by vacuum distillation. The undissolved fraction yielded 2.9 parts of chlor-acetone and 57.6 parts of an oil having a viscosity of 459 seconds Saybolt universal at F., a specific gravity of 0.936 and a viscosity-gravity constant of 0.843. The dissolved fraction yielded 297.1 parts of chlor-acetone and 42.4 parts of oil having a viscosity of 1542 seconds Saybolt universal at 100 F., a specific gravity of 0.9725 and a viscosity-gravity constant of 0.924.

When 100 parts of a Mid-Continent distillate having a viscosity of 154 seconds Saybolt universal at 210 F., a specific gravity of 0.9176 at 60 F. and a viscosity-gravity constant of 0.836 was extracted in the above described manner with 300 parts of ethyl chloracetate, there resulted an undissolved oil fraction comprising 72% of the stock and having a viscosity of 141 seconds Saybolt universal at 210 F., a specific gravity of 0.9071 and a viscosity-gravity constant of 0.824. The dissolved oil fraction comprising 28% of the original stock had a viscosity of 129 seconds Saybolt universal at 210 F., a specific gravity of 0.9446 and a viscosity-gravity constant of 0.875. I

Table 1, given below, is a summary of extraction data comparing a group of aliphatic oxyand oxo-solvents with their corresponding halogen derivatives. The data, in each case,

represents a single extraction with the solventative only oneaextractionwas made, the-ratio-iof: solvent to oilbeing 3:1.

- ZHerein,: -and in the appendedclaims, the term ivisc'ousoil:is .to beunderstood as comprehendw Table I v01. ofun- Ratio vol. Vis'.-grav Xigfifl Via-gray, dissolved start that? ft ar fear has. stock stock roduct .solved oil solvent employed Ethyl acetate; 0. 900" 1 0; s36 "0. 880 0. 912 Ethylchloracetate Y 1 0. 836 0. 5584f 0. 869 Eth acetata 3 0. 836 0. 871, 0. 247 Ethyl chloraceta 3 0.836 0.875 0. 240 Acetone 1 0. 874 O. 932 0. 834 Chl0racetone 1 0. 874 1 0. 950. 0.787 Acetone 2 0. 874 0. 921 0. 328 chloracetone 3 O. 874 i O. 924 I 0. 192 Propyl alcohol 0. 804 3 0. 874 0. 884 0.128,. 2, 3 dibrom propyl alcohol. 2. 083 3 0. 874 0. 941 0. 190

The above table shows that halogen'ation increases the specific gravity of the'aliphatic oxyand oxo-compounds very substantially, which fact is important in thatthe specific gravity differential between solvent and oil is increased, thereby causing an increased rate of separation of the oil and solvent layers. It is desirable to have the specific gravity of the selective solvent as widely different from the specific gravity of the oil as possible, in order to bring about a rapid separation of the layers. The specific gravity of the solvent is of prime importance where the extraction process is to be carried on continuously, as the rate of thru-put of the oil, 1. -e., the capacity of the apparatus is determined by the readiness and rapidity of separation of the dissolved from the undissolved layer, which is a function of the gravity differential between dissolved and undissolved layers.

While halogenation, in general, improves the selectivity of the aliphatic solvents, the increase in specific gravity is perhaps of greater importance. The selective efficiency of the solvent may be of little practical importance if the specific gravity of such solvent does not diifer sufficiently from that of the oil to allow a ready and rapid separation of the undissolved oil and solvent layers. The question of specific gravity differential between solvent and oil may well be the controlling factor as to the adaptability or preclusion of such solvent for practical use in selective extraction, particularly in a continuous extraction process.

The halogen derivatives of the aliphatic oxyand oxo-compounds have, in general, a higher specific gravity than the corresponding non-halogenated solvents, and, as a class, are capable of producing, in a single extraction, a dissolved and an undissolved oil fraction having a greater viscosity-gravity constant difierential than the nonhalogenated solvents are capable of producing.

From the foregoing data it will be seen that by extraction of a mineral oil with a halogen derivative of an aliphatic oxyor oxo-compound there may be obtained oil fractions which are respectively more paraflinic and more naphthenic than the original oil. By repetition of the extraction process or by a continuous countercurrent process, the undissolved oil fraction may be rendered increasingly parafiinic, as evidenced by a progresing an oil of substantial viscosity,-i; 'e., of the-order of50'seconds Saybolt universal at 109? F'., or more. What I claim is: Y

'I.'"'I'lie process for separating mineral'oils containing liquid parafiinic' and naphthenic hydrocarbons into fractions which comprises bringing the oil into contact with a solvent from the group of halogenated oxygen containing aliphatic compound consisting of ethyl chloracetate, chloracetone, and dibrom propyl alcohol, thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in the said solvent, separating the solution so formed from the remainder of the oil, and. distilling the solvent from both of the portions of the oil, thereby to obtain fractions of the oil respectively richer in liquid paraffinic and naphthenic hydrocarbons.

2. In the art of refining mineral lubricating oil containing liquid paraffinic and naphthenic hydrocarbons, the step of fractionally extracting the oil with a solvent from the group of halogenated oxygen containing aliphatic compounds consisting of ethyl chloracetate, chloracetone, and dibrom propyl alcohol, to effect a separation of fractions respectively richer in liquid paraifinic and naphthenic compounds.

3. In the art of refining mineral oils, the process which comprises adding a solvent from the group of halogenated oxygen-containing aliphatic compounds consisting of ethyl chloracetate, chloracetone and dibrom propyl alcohol to an oil containing liquid parafiinic and naphthenic ess which comprises adding a solvent from the group of halogenated oxygen-containing aliphatic compounds consisting of ethyl chloracetate, chloracetone and dibrom propyl alcohol to an oil containing liquid paraffinic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solution to form a two layer system, removing the lower layer, and similarly re-treating the upper layer with said solvent.

5. The process of treating a viscous fraction of a crude oil of one type containing liquid parafinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different type having a greater content of liquid paraffinic hydrocarbons, which comprises extracting the viscous fraction with a solvent from the groupof halogenated oxygen-containing aliphatic compounds consisting of ethyl chloracetate, chloracetone and dibrom propyl alcohol, and separating the oil so treated into portions respectively richer in liquid parafinic and naphthenic hydrocarbons.

6. In the art of refining mineral oils, the process which comprises bringing a solvent from the group of halogenated oxygen-containing aliphatic compounds consisting of ethyl chloracetate, chloracetone and dibrom propyl alcohol, into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing parafiinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic components, thereafter removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby to produce an oil such as is normally obtained from Pennsylvania type crude by distillation.

'7. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing paraflinic and naphthenic hydrocarbons into contact with a solvent from the group of halogenated oxygen-containing aliphatic compounds consisting of ethylchloracetate, chloracetone and dibrom propyl alcohol, thereby to effect solution of a portion richer in naphthenic hydrocarbons in the solvent, separating the solution so formed from the remainder of the oil, and retreating the oil remaining with additional amounts of said solvent.

8. The process of decreasing the viscosity-gravity constant of a viscous mineral oil which comprises extracting the oil with a solvent from the group of halogenated oxygen-containing aliphatic compounds consisting of ethyl chloracetate, chloracetone and dibrom propyl alcohol.

9. The process of treating a viscous hydrocarbon oil having a viscosity-gravity constant between substantially 0.835 and 0.875 to reduce the viscosity-gravity constant by at least 0.015, which comprises extracting said viscous oil with a solvent from the group of halogenated oxygen-containing compounds consisting of ethyl chloracetate, chloracetone and dibrom propyl alcohol.

SEYMOUR W. FERRIS. 

